Rectangilar-Ribbed Profile Tubular Core and Method

ABSTRACT

Disclosed is a tubular core on which sheets of metal or other material can be wound and supported, for shipment, handling and dispersal, and a method for forming the core. The core comprises a metal sheet or strip which has a rectangular-ribbed cross-sectional profile of flattened ribs, and which is wound spirally into a tubular configuration. The core is formed by passing the strip through a plurality of roll-forming stands, to initiate forming and progressively form an arcuate ribbed sinusoidal profile, then a final roll-forming pass is used (or several such passes are used) to flatten the ribs of the profile so that the rectangular flattened ribs collectively form a support surface for the sheets which are wound and supported on the core.

This patent application claims the benefit of prior U.S. provisional patent application No. 62/231,495, filed Jul. 7, 2015, which provisional patent application is hereby incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

The words “pipe” and “tube” are used interchangeably here.

This invention relates to relatively small diameter pipes or tubes and in particular to tubular cores on which sheets of metal or other material can be wound for shipment, handling and dispersal. As used here, the word dispersal includes mounting a core and a sheet wound thereon on an uncoiler, then rotating the core to unwind the sheet and feed the sheet to apparatus for forming the sheet into other goods (beverage cans, automotive body parts, etc.).

Cores comprising paper or cardboard and glue are widely used for the above purposes. For example, beverage can stock material can be manufactured using cores which are formed to various diameters, for example, inside diameters of 16″, 20″ or 24″, from paper fiber about 0.5″ to 1″ thick. These cores are not easily recyclable and must be disposed of in dumps or landfills, with the attendant cost and detrimental impact on the environment. These cores can be crushed to facilitate storage and disposal, but this can be a problem because of their bulk and the difficulty in crushing them.

Tubes or pipes formed from metal strips are known in the art. See, for example, commonly assigned U.S. Pat. Nos. 3,940,962 and 3,247,692 in the name of Paul K. Davis, which disclose the so-called three-roll free forming method and apparatus for forming pipes. According to these patents, an elongated strip of metal is advanced in a generally planar path along its longitudinal axis and into forming stands which form the strip into a profile, then the profiled strip is fed continuously into a tube forming machine at which the strip is curled or wrapped between three sets of rollers (lead, mandrel and buttress rollers) into helical tubes. The sets of rollers extend in rows at an angle relative to the longitudinal axis of the incoming strip, the helix angle, which is so related to the radius of the helical convolutions and the width of the incoming strip that the trailing edge of a preceding portion of the strip converges into contact with the leading edge of the following portion of the strip. The '962 patent also teaches diameter control. The tubes formed in accordance with the '692 and '962 patent are used in a variety of applications. U.S. Pat. Nos. 3,940,962 and 3,247,692 are hereby incorporated by reference in their entirety.

Metal tubes or pipes have the potential for use as small diameter recyclable cores, but to date their use has been limited because of the difficulty of forming metal into small diameter tubes. For a given sheet thickness, smaller diameter tubes require greater force to deform the sheet and form the pipe. Also, decreasing the thickness of the tube wall (the thickness of the tube-forming sheet or strip) increases the tendency to buckle. In addition, it is more difficult to control the diameter and to maintain a consistent lockseam as the tube is formed.

Commonly assigned U.S. Pat. No. 5,074,138 in the name of Robert F. Miller describes an improvement of the invention disclosed in incorporated U.S. Pat. No. 3,247,692. The improvement involves the design and manufacture of a lockseam pipe which has a corrugated, sinusoidal profile comprising arcuate/semi-circular ridges and grooves, and which is adapted for improving the physical characteristics of the pipe and the strength of the lockseam. U.S. Pat. No. 5,074,138 is hereby incorporated by reference in its entirety.

SUMMARY OF THE INVENTION

The present invention is embodied in the structure and manufacture of a thin wall bellows tube or pipe which is formed from a metal strip having a flattened sinusoidal corrugated profile. In one aspect the tube is used as a core onto which a sheet of material can be wound or coiled for shipment, handling and dispersal. In a particular aspect this invention relates to the structure and manufacture of such a core from strips of metal and, more particularly, from a thin strip of metal such as aluminum.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a transverse cross-section of a metal strip having a transverse profile formed therein in accordance with the present invention, preparatory to the strip being helically wound into a tubular core.

FIG. 2 depicts a strip such as that of FIG. 1 being wound into a helical tubular core.

FIG. 3 is a transverse cross-section of two adjacent windings of a strip such as that of FIG. 1 where the strip is helically wound to form a core such as that of FIG. 2, and the leading edge of one winding of the strip is joined by a lockseam to the trailing edge of the adjacent winding.

DETAILED DESCRIPTION

The pipe forming in accordance with the present invention can be achieved via fixed forming using a forming shoe with a predetermined inside diameter to provide the desired pipe diameter, or by free forming using several sets of roller dies of different sizes to achieve pipes of different diameters, by adjusting the helix angle or by a combination thereof.

The illustrative equipment and process described here use, and are improvements of, the multi-pass roll former, three roll, free forming system disclosed in commonly assigned and incorporated U.S. Pat. Nos. 3,940,962 and 3,247,692 as specifically adapted to bellows pipe (relatively small diameter corrugated pipe) in commonly assigned and incorporated U.S. Pat. No. 5,074,138.

The '962 patent describes corrugating and forming sections which can continuously corrugate a strip or sheet of material and form the corrugated strip into a pipe. The corrugating section comprises multiple stands of rolls which form a curved sinusoidal profile in the driven strip. The corrugated strip is then fed to the three-roll forming section which deforms or curls the advancing strip into a cylinder or pipe along which the opposite strip edges form a mating spiral, then seals the mating strip edges into a continuous lockseam which wraps along the pipe. The continuous corrugated pipe is then advanced to a discharge station where the pipe can be cut into lengths and received on a run-out table for any further processing and handling.

The illustrative equipment and process described here are an improvement of the approach described in the '962 patent in that in accordance with the present invention multiple passes are used to roll-form a flat metal sheet or strip into an arcuate sinusoidal profile, then at least one final pass is used to deform the arcuate sinusoidal profile of the strip into a flattened, generally rectangular profile.

According to the present invention and referring to FIG. 1, initially a flat metal strip or sheet is roll-formed to a desired profile.

In a presently preferred embodiment of the present invention, initially the flat metal strip is passed through multiple roll-forming stands, to form the strip into a transverse profile comprising arcuate ribbed sinusoidal corrugations, then prior to forming the strip into a tube or core, the strip is passed through a final roll-forming stand or stands to flatten the strip profile, that is, to reform the strip profile into a rectangular-ribbed profile. Illustratively and presently, nine passes are used to roll-form the strip into an arcuate sinusoidal transverse profile, then a tenth pass is used to deform and thereby flatten the profile into the rectangular-ribbed profile 10.

The above profile-forming method results in the profile 10 shown in FIG. 1 which comprises alternating ribs in the form of upwardly extending ridges 11 and downwardly extending grooves 12. The ridges 11 have flat top or upper surfaces 13 and the grooves 12 have flat bottom or lower surfaces 14. A downward (or upward) opening flange or tab 16 is formed extending along one longitudinal edge of the strip or sheet transverse to the width of the strip and an opposite opening upward (or downward) extending tab 17 is formed extending along the opposite longitudinal edge of the strip.

To form the profiled strip into a tube or core, and referring to FIG. 2, the rectangular-ribbed profile strip or sheet 10 is wrapped using helical forming apparatus into a cylindrical pipe or core 20 of the desired diameter and, as shown in FIG. 3, the mating tabs 16 and 17 are compressed together to form a four-ply interlocked helical seam 21 which wraps around the pipe lengthwise along the pipe. The strip edges are held together via a continuous mechanical lockseam which is pushed together to lock the lockseam.

In the formed pipe 20, the spaced-apart adjacent flat surfaces 14 of the rectangular grooves 12 form the outside surface 22 of the core 20 and the spaced-apart flat surfaces 13 of the rectangular ridges 11 form the inside surface 23 of the core.

The strip 10 illustrated in FIG. 1 is symmetrical top-to-bottom and thus can be reversed top-to-bottom during the pipe wrapping process depicted in FIG. 2. Then the spaced-apart flat ridge surfaces 13 form the outer surface 22 of the core and the spaced-apart flat groove surfaces 14 form the inside surface of the core.

Referring to the FIG. 3 cross-section of the core 20 depicted in FIG. 2, in the pipes made in accordance with the present invention, the ridges and grooves maintain their generally rectangular, ribbed shape and form an open structure with spacing between the adjacent ridges 11 as well as spacing between the adjacent grooves 12. This is unlike prior designs which use non-rectangular shapes and/or an additional deformation step to form a continuous outer surface in order to provide the required strength and integrity and to provide ample flat surface area for sheet support. The outer surface is interrupted by the spacing of the inside rectangles. In an embodiment, the width of the ridges and the grooves, and the spacing between adjacent ridges and between adjacent grooves, are all equal.

Embossments or reinforced embossments can be added to the ribs, e.g., to the legs, to enhance core strength.

EXAMPLES

The above design and method have been used to form cylindrical cores of different sizes.

Specifically, in strips or sheets 10 of aluminum which were 0.010″ to 0.023″ thick and 3⅝″ wide, ridges 11 and grooves 12 were formed which were 0.27″ in height from the top of the a ridge to the bottom of the adjacent groove. Both the ridges and the grooves were 0.27″ wide and were spaced apart 0.27″ from adjacent ridges and grooves, respectively. See FIG. 1. The rectangular corrugated strips or sheets 10 were fed to the three-roll apparatus using helix angles ≧60° measured from the axis of the outgoing pipe to form continuous length pipes of 16″, 20″ and 24″ inside diameters. The pipes 20 were then cut into various lengths for use as recyclable cores onto which sheets of metal such as aluminum were to be wound for handling and dispersal.

Other dimensions and materials will be readily adapted to the invention described here by those of usual skill in the art. For example the invention can be used to form pipes approximately 6″ in diameter and greater. For a given sheet width, increasing the helix angle increases the pipe diameter. For a given pipe diameter, increasing the sheet width reduces the required helix angle. Increasing the strip width tends to increase the pipe wrapping/manufacturing speed and to decrease the number of seams in a given length of pipe. 

What is claimed is:
 1. A method for forming a metal strip into a cylindrical core, comprising: passing an elongated metal strip having width and length and opposite longitudinal edges through a multiplicity of forming stands each of which forms curved longitudinally extending sinusoidal corrugations in said strip or changes the size of existing curved corrugations or both, then passing the strip through at least one final forming stand for flattening the corrugations, wherein upon completion of the corrugation forming process a plurality of the rectangular corrugations as-formed along the width of the strip comprise longitudinally extending, alternating ribs including upwardly extending ridges and downwardly extending grooves, the ridges and grooves comprising generally vertical spaced-apart sidewalls with the ridges further comprising longitudinally extending, flattened, spaced-apart top surfaces extending between adjacent ridge sidewalls and the grooves further comprising longitudinally extending, flattened, spaced-apart bottom surfaces extending between adjacent groove sidewalls, the flattened ridges and flattened grooves together forming a rectangular ribbed cross sectional profile extending along the width of the strip transverse to the length thereof; forming the opposite longitudinal edges of the as-formed corrugated metal strip into flanges adapted for forming an interlocking seam; helically coiling the as-formed corrugated strip into a cylinder having a longitudinal axis and an outer surface defined by flat, spaced-apart surfaces selected from the top surfaces and the bottom surfaces; and compressing the opposite edge flanges together thereby forming an interlocking seam extending in a spiral around the cylinder along the longitudinal axis thereof.
 2. The method of claim 1 wherein the metal strip is aluminum and is 0.005″ to 0.050″ thick.
 3. The method of any of claims 1 and 2 wherein during the helical coiling step, the metal strip is oriented at a helix angle of approximately 60° or greater relative to the longitudinal axis.
 4. A cylindrical core, comprising: an elongated metal strip having width and length and being helically coiled into a cylinder, the cross-sectional profile of the strip along the width thereof transverse to the length thereof including corrugations comprising longitudinally extending alternating ribs including upward extending ridges alternating with downward extending grooves, the ridges having longitudinally extending, generally flattened, spaced-apart top surfaces, the grooves having longitudinally extending, generally flattened, spaced-apart bottom surfaces, and the flattened ridges and the flattened grooves together forming a flat ribbed corrugated transverse cross section; said cylinder having an outer surface formed by flat spaced-apart surfaces selected from the top surfaces of the ridges and the bottom surfaces of the grooves; and a lockseam of joined opposite edges of the metal strip, the lockseam extending in a spiral around the cylinder along the longitudinal axis thereof.
 5. The core of claim 4 wherein the metal strip is aluminum and is 0.005″ to 0.050″ thick.
 6. The core of claim 5 wherein the pipe diameter is at least approximately 6″.
 7. The core of any of claims 4, 5 and 6 wherein prior to forming the cylinder the aluminum strip is approximately 0.023″ thick and approximately 3⅝″ wide; the vertical dimension between adjacent top and bottom surfaces of the as-formed cylinder is approximately 0.27″; the width of the flat ridge surfaces is approximately 0.027″, the distance between adjacent flat ridge surfaces is approximately 0.027″; the width of the flat groove surfaces is approximately 0.027″, the distance between adjacent flat ridge surfaces is approximately 0.027″; and the diameter of the as-formed cylinder is within the range approximately 16″-24″.
 8. The core of claim 7 further comprising embossments in the legs of the ribs. 